Magmatic evolution of the southern Great Bear continental arc, northwestern Canadian Shield: geochronological constraints

2001 ◽  
Vol 38 (5) ◽  
pp. 767-785 ◽  
Author(s):  
S S Gandhi ◽  
J K Mortensen ◽  
N Prasad ◽  
O van Breemen
Keyword(s):  
Passive Margin ◽  
Calc Alkaline ◽  
Slave Craton ◽  
Continental Arc ◽  
Felsic Volcanism ◽  
Two Samples ◽  
Intrusive Rocks ◽  
Geochronological Constraints ◽  
Age Range ◽  
Age Constraints

The calc-alkaline Great Bear continental arc in the Wopmay Orogen developed after a collision ca. 1890 Ma of the Archean Slave craton with the Paleoproterozoic Hottah terrane to the west. U–Pb zircon dating of three volcanic and six intrusive rocks from the southern part of the arc shows four stages of development: (i) intrusion of a few small sodic leucogranite plutons at 1873 ± 2 Ma into a previously folded metasedimentary sequence; (ii) abundant calc-alkaline felsic volcanism and subvolcanic intrusions during the period 1870–1866 Ma, bracketed by five ages; (iii) intrusion of large calc-alkaline granitic plutons, including the Marian River batholith, dated by zircon and titanite from two samples at 1866 +2–3 Ma; and (iv) emplacement of the potassic Faber Lake rapakivi granite at 1856 +2–3 Ma. The arc was developed on the Hottah terrane due to easterly subduction of an oceanic plate under the amalgamated Slave craton – Hottah terrane. The oldest exposed rocks in the southern part of the arc are remnants of a Paleoproterozoic platformal sequence. They were regarded previously as equivalents of the initial passive margin sequence on the Slave craton, but are interpreted here as part of the Hottah terrane. The ages reported here are comparable with earlier data from the northern part of the arc, which show an age range from 1875 to 1840 Ma and also identify two suites of compositionally and temporally distinct granites. The age constraints show that the Great Bear arc evolved rapidly in time from sodic through calc-alkaline, and then, with a pause, to potassic composition.

scholarly journals Zircon geochronology of intrusive rocks from Cap de Creus, Eastern Pyrenees

2014 ◽  
Vol 151 (6) ◽  
pp. 1095-1114 ◽  
Author(s):  
ELENA DRUGUET ◽  
ANTONIO CASTRO ◽  
MARTIM CHICHORRO ◽  
M. FRANCISCO PEREIRA ◽  
CARLOS FERNÁNDEZ
Keyword(s):  
Tectonic Evolution ◽  
Lower Permian ◽  
Zircon Geochronology ◽  
Early Permian ◽  
Calc Alkaline ◽  
Crustal Shortening ◽  
Eastern Pyrenees ◽  
Structural Relationships ◽  
Two Samples ◽  
Intrusive Rocks

AbstractNew petrological and U–Pb zircon geochronological information has been obtained from intrusive plutonic rocks and migmatites from the Cap de Creus massif (Eastern Pyrenees) in order to constrain the timing of the thermal and tectonic evolution of this northeasternmost segment of Iberia during late Palaeozoic time. Zircons from a deformed syntectonic quartz diorite from the northern Cap de Creus Tudela migmatitic complex yield a mean age of 298.8±3.8 Ma. A syntectonic granodiorite from the Roses pluton in the southern area of lowest metamorphic grade of the massif has been dated at 290.8±2.9 Ma. All the analysed zircons from two samples of migmatitic rocks yield inherited ages from the Precambrian metasedimentary protolith (with two main age clusters at c. 730–542 Ma and c. 2.9–2.2 Ga). However, field structural relationships indicate that migmatization occurred synchronously with the emplacement of the quartz dioritic magmas at c. 299 Ma. Thus, the results of this study suggest that subduction-related calc-alkaline magmatic activity in the Cap de Creus was coeval and coupled with D2 dextral transpression involving NNW–SSE crustal shortening during Late Carboniferous – Early Permian time (c. 299–291 Ma). Since these age determinations are within the range of those obtained for undeformed (or slightly deformed) calc-alkaline igneous rocks from NE Iberia, it follows that the Cap de Creus massif would represent a zone of intense localization of D2 transpression and subsequent D3 ductile wrenching that extended into the Lower Permian during a transitional stage between the Variscan and Cimmerian cycles.

SHRIMP U–Pb geochronology of detrital zircons from the Treasure Lake Group — new evidence for Paleoproterozoic collisional tectonics in the southern Hottah terrane, northwestern Canadian Shield

2005 ◽  
Vol 42 (5) ◽  
pp. 833-845 ◽  
Author(s):  
S S Gandhi ◽  
O van Breemen
Keyword(s):  
Middle Part ◽  
Detrital Zircons ◽  
Slave Craton ◽  
The North ◽  
Quartz Arenite ◽  
Continental Arc ◽  
Wide Range ◽  
Depositional Age ◽  
Age Range ◽  
New Evidence

The recently defined Treasure Lake Group is a platformal sedimentary sequence more than 3 km thick that was deformed and metamorphosed prior to formation of the Great Bear continental arc during 1875–1845 Ma. The group is exposed as remnants in the southern part of the arc. Its basement is not exposed, but is interpreted to comprise the Paleoproterozoic Hottah terrane, which is exposed at Hottah Lake in the northern part of the arc. Studies in that region show that the Hottah terrane collided with the Archean Slave craton to the east ca. 1883 Ma following reversal of subduction polarity from west to east. Continued eastward subduction under the collision zone formed the Great Bear arc. The present study was undertaken to determine the age and provenance of the Treasure Lake Group. Thirty-nine detrital zircon grains from a sample of a quartz arenite unit in the middle part of the Treasure Lake Group were analyzed by SHRIMP (sensitive high-resolution ion microprobe). They show an age range from ca. 2729 to ca. 1880 Ma, with main modes at ca. 1895, 1985, 2090, and 2330 Ma. These data confirm a mainly Paleoproterozoic provenance for the group. The youngest group of five zircon analyses places the maximum depositional age at 1886 ± 8 Ma. The Treasure Lake Group is close to the north-trending Wopmay medial zone formed during collision of the Hottah terrane and the Slave craton. Deformation and metamorphism of the group can now be attributed to the collisional event. The group may in part be coeval with the Bell Island Bay and Akaitcho groups of the northern Hottah terrane, the lower parts of which were deposited ca. 1900 Ma. The wide range of detrital zircons ages found in this study is interpreted to reflect a complex Paleoproterozoic evolution of the Hottah terrane.

scholarly journals Geochemical Classification and Geotectonic Setting of Granitic Gneisses from Southeastern Margin of Western Nigeria Basement

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Mohammed Olatoye Adepoju ◽  
Yinusa Ayodele Asiwaju-Bello
Keyword(s):  
Inductively Coupled Plasma ◽  
Tectonic Setting ◽  
Calc Alkaline ◽  
Granitic Gneiss ◽  
Basement Complex ◽  
Southwestern Nigeria ◽  
Inductively Coupled ◽  
Continental Arc ◽  
Southeastern Margin ◽  
Geochemical Classification

Chemical whole-rock major oxides and some trace element analyses were done on granitic gneiss rocks located on the southeastern margin of western Nigeria Basement Complex, exposed in parts of Dagbala-Atte District, southwestern Nigeria. This was meant to classify the rocks and to understand the tectonic setting in order to evaluate their crustal evolution. The chemical analyses were done using inductively-coupled plasma mass spectrometer. From the results obtained, these rocks classified into calc-alkaline to shoshonite series with metaluminous to peraluminous varieties, they are I-type granitoids of feroan composition. The granitic gneisses formed from metamorphism of granite and granodiorite. Tectonically, most of the rock samples plotted in the field of island arc, continental arc and continental-collisional granitoids, which indicated that the protolith granite and granodiorite are orogenic and are arc related inferring arc tectonic setting.

Lower Palaeozoic and Precambrian igneous rocks from eastern England, and their bearing on late Ordovician closure of the Tornquist Sea: constraints from U-Pb and Nd isotopes

1993 ◽  
Vol 130 (6) ◽  
pp. 835-846 ◽  
Author(s):  
S. R. Noble ◽  
R. D. Tucker ◽  
T. C. Pharaoh
Keyword(s):  
Volcanic Rocks ◽  
Igneous Rocks ◽  
Calc Alkaline ◽  
Nd Isotopes ◽  
Nd Isotope ◽  
Magmatic Arc ◽  
The North ◽  
Basement Rocks ◽  
Continental Arc ◽  
Lower Palaeozoic

AbstractThe U-Pb isotope ages and Nd isotope characteristics of asuite of igneous rocks from the basement of eastern England show that Ordovician calc-alkaline igneous rocks are tectonically interleaved with late Precambrian volcanic rocks distinct from Precambrian rocks exposed in southern Britain. New U-Pb ages for the North Creake tuff (zircon, 449±13 Ma), Moorby Microgranite (zircon, 457 ± 20 Ma), and the Nuneaton lamprophyre (zircon and baddeleyite, 442 ± 3 Ma) confirm the presence ofan Ordovician magmatic arc. Tectonically interleaved Precambrian volcanic rocks within this arc are verified by new U-Pb zircon ages for tuffs at Glinton (612 ± 21 Ma) and Orton (616 ± 6 Ma). Initial εNd values for these basement rocks range from +4 to - 6, consistent with generation of both c. 615 Ma and c. 450 Ma groups of rocksin continental arc settings. The U-Pb and Sm-Nd isotope data support arguments for an Ordovician fold/thrust belt extending from England to Belgium, and that the Ordovician calc-alkaline rocks formed in response to subductionof Tornquist Sea oceanic crust beneath Avalonia.

New age constraints on magmatism and metamorphism in the Morin terrane (Grenville Province, Quebec)

2022 ◽  
Author(s):  
William H Peck ◽  
Matthew P Quinan
Keyword(s):  
Shear Zone ◽  
Granulite Facies ◽  
Western Boundary ◽  
Grenville Province ◽  
Granulite Facies Metamorphism ◽  
Metamorphic History ◽  
Crustal Block ◽  
Two Samples ◽  
Western Side ◽  
Age Constraints

The Morin terrane is an allochthonous crustal block in the southwestern Grenville Province with a relatively poorly-constrained metamorphic history. In this part of the Grenville Province, some terranes were part of the ductile middle crust during the 1.09–1.02 Ga collision of Laurentia with the Amazon craton (the Ottawan phase of the Grenvillian orogeny), while other terranes were part of the orogen’s superstructure. New U-Pb geochronology suggests that the Morin terrane experienced granulite-facies metamorphism during the accretionary Shawinigan orogeny (1.19–1.14 Ga) and again during the Ottawan. Seven zircon samples from the 1.15 Ga Morin anorthosite suite were dated to confirm earlier age determinations, and Ottawan metamorphic rims (1.08–1.07 Ga) were observed in two samples. U-Pb dating of titanite in nine marble samples surrounding the Morin anorthosite suite yielded mixed ages spanning between the Shawinigan and Ottawan metamorphisms (n=7), and predominantly Ottawan ages (n=2). Our results show that Ottawan zircon growth and resetting of titanite ages is spatially heterogeneous in the Morin terrane. Ages with a predominantly Ottawan signature are recognized in the Morin shear zone, which deforms the eastern lobe of the anorthosite, in an overprinted skarn zone on the western side of the massif, and in the Labelle shear zone that marks its western boundary. In the rest of the Morin terrane titanite with Shawinigan ages appear to have been only partially reset during the Ottawan. Further work is needed to better understand the relationship between the character of Ottawan metamorphism and resetting in different parts of the Morin terrane.

Radiocarbon dating of textile Components from Historical silk costumes and other cloth products in the Ryukyu Islands, Japan

Radiocarbon ◽  
2019 ◽  
Vol 61 (6) ◽  
pp. 1663-1674
Author(s):  
Toshio Nakamura ◽  
Takako Terada ◽  
Chikako Ueki ◽  
Masayo Minami
Keyword(s):  
Radiocarbon Dating ◽  
Middle Age ◽  
Historical Record ◽  
Ryukyu Islands ◽  
High Status ◽  
15Th Century ◽  
Religious System ◽  
Two Samples ◽  
The Ryukyu Islands ◽  
Age Range

ABSTRACTIn our research on traditional clothing and accessories in the Ryukyu Islands of Japan, we have collected cloth fragments from traditional Ryukyuan costumes and other fabric products for radiocarbon (14C) dating. In this study, the cloth samples from historical costumes of noro priestesses (two samples), men and women from high-status families (five samples), and non-costume cloth products (seven samples), belonging to the traditional hereditary religious system of the ancient Ryukyu Kingdom, which lasted from approximately the 14th century AD to 1829 were analyzed. One extra sample originated from a silk shawl known as a Manila shawl. The oldest among the 15 samples dates back to the mid-15th century, but some newer ones belong to the unclear calibrated age range of AD 1650–1950. The measured dates are very consistent with the historical record, suggesting that acetone and acid-alkali-acid treatments are an adequate cleaning method for radiocarbon dating of silk and cotton samples produced in the late Middle Age and later.

scholarly journals Acceptance of a New Food Enriched in β-Glucans among Adolescents: Effects of Food Technology Neophobia and Healthy Food Habits

Foods ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 433 ◽  
Author(s):  
Cristina Proserpio ◽  
Ella Pagliarini ◽  
Monica Laureati ◽  
Beatrice Frigerio ◽  
Vera Lavelli
Keyword(s):  
Wheat Flour ◽  
Eating Behavior ◽  
Food Habits ◽  
Control Sample ◽  
Healthy Food ◽  
Food Technology ◽  
Unhealthy Eating ◽  
Healthy Eating Behavior ◽  
Two Samples ◽  
Age Range

The aim of the present study was to evaluate adolescents’ acceptability of a novel flat bread modified by substituting a part of the wheat flour content with a Pleurotus ostreatus powder rich in β-glucans, which can potentially provide health benefits. The effects of food technology neophobia and adolescents’ food habits on hedonic perception of the developed product was also investigated. Two hundred and two adolescents (age range: 13–18 years; girls: 49.5%; boys: 50.5%) evaluated their liking of two flat breads, one with mushroom powder added and one control sample with only wheat flour. Sample acceptance was studied in relation to age, gender, neophobic traits and healthy food habits. The results showed that, even if the sample with mushroom powder added was generally well accepted, there were different hedonic responses among adolescents according to their food technology neophobia level and healthy habits. In particular, adolescents with a low food technology neophobia level and healthy eating behavior mostly appreciated the sample with mushroom powder added, whereas subjects with neophobic and unhealthy eating behavior gave comparable hedonic scores to the two samples. Moreover, a negative correlation was found between food technology neophobia level and healthy food habits. In conclusion, it is possible to develop a β-glucan-enriched product appreciated by adolescents using a sustainable ingredient. The developed product may be used to achieve the daily recommended intake of β-glucans by adolescents.

scholarly journals Intra-individual variation of plasma trimethylamine-N-oxide (TMAO), betaine and choline over 1 year

2017 ◽  
Vol 55 (2) ◽  
Author(s):  
Tilman Kühn ◽  
Sabine Rohrmann ◽  
Disorn Sookthai ◽  
Theron Johnson ◽  
Verena Katzke ◽  
...  
Keyword(s):  
Individual Variation ◽  
Plasma Levels ◽  
Low Density Lipoprotein ◽  
Plasma Concentrations ◽  
Density Lipoprotein ◽  
Correlation Coefficients ◽  
Reactive Protein ◽  
Fasting Plasma ◽  
Two Samples ◽  
Age Range

AbstractBackground:Circulating trimethylamine-Methods:We measured fasting plasma levels of TMAO and two of its precursors, betaine and choline by LC-MS, in two samples of 100 participants of the European Investigation into Cancer and Nutrition (EPIC)-Heidelberg study (age range: 47–80 years, 50% female) that were collected 1 year apart, and assessed their intra-individual variation by Spearman’s correlation coefficients (ρ).Results:Correlations of metabolite concentrations over 1 year were at ρ=0.29 (p=0.003) for TMAO, ρ=0.81 (p<0.001) for betaine, and ρ=0.61 (p<0.001) for choline. Plasma levels of TMAO were not significantly associated with food intake, lifestyle factors, or routine biochemistry parameters such as C-reactive protein (CRP), low-density lipoprotein (LDL)-cholesterol, or creatinine.Conclusions:In contrast to fasting plasma concentrations of betaine and choline, concentrations of TMAO were more strongly affected by intra-individual variation over 1 year in adults from the general population. The modest correlation of TMAO levels over time should be considered when interpreting associations between TMAO levels and disease endpoints.

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